1. Field of the Invention
The present invention relates to a direct backlight module, and in particular to a direct backlight module supporting the diffuser and illumination tubes simultaneously to overcome bending of the diffuser and illumination tubes due to thermal expansion and contraction and insufficient rigidity thereof.
2. Description of the Related Art
FIG. 1 is a cross section showing a conventional direct backlight module 1. The conventional direct backlight module 1 includes a diffuser 11, a reflecting plate 12, a prism 17, a diffusing plate 18, two supports 13 and a plurality of illumination tubes 14. The reflecting plate 12 is disposed under the diffuser 11. The prism 17 is disposed on the diffuser 11. The diffusing plate 18 is disposed on the prism 17. The supports 13 are disposed on the reflecting plate 12 and located between the diffuser 11 and the reflecting plate 12. The plural illumination tubes 14 are disposed between the diffuser 11 and the reflecting plate 12.
As shown in FIG. 1, in order to protect the diffuser 11 from bending, the supports 13 are disposed between the diffuser 11 and the reflecting plate 12 to support the diffuser 11. Thus, the optical character of the direct backlight module 1 is not deteriorated and even the illumination tubes 14 are not damaged by the bent diffuser 11. Nevertheless, when the size of the LCD panel 15 increases, the illumination tube 14 also becomes larger. Thus, the illumination tube 14 is bent and deformed due to its weight, deteriorating the optical character of the direct backlight module 1.
FIG. 2 is a cross section showing another conventional direct backlight module 2. In order to overcome the aforementioned deformation of the illumination tubes 14 of the direct backlight module 1, a support 23 is disposed under the illumination tube 22 of the direct backlight module 2. Nevertheless, as shown in FIG. 2, when the size of the LCD panel (not shown) increases, the diffuser 21 also becomes large. Thus, the diffuser 21 is bent and deformed, deteriorating the optical character of the direct backlight module 2.
Consequently, the invention provides a direct backlight module supporting the diffuser and the illumination tubes simultaneously. The diffuser and illumination tubes are not bent and deformed due to insufficient rigidity thereof even when the LCD panel or the diffuser is large. Further, the diffuser and the illumination tubes are not deformed due to thermal expansion and contraction even when the direct backlight module works for a long period of time. Thus, the optical character of the direct backlight module is not deteriorated.